1. Field of the Invention
The invention relates to a side impact beam as a reinforcement component of a motor vehicle, in particular, of a motor vehicle door, which over the predominant portion of its length has a section of sheet metal which, in cross-section, has a hat-shape comprised of a stay, two legs, and two flanges.
2. Description of the Related Art
Side impact beams are provided as a protection for vehicle passengers in regard to injuries resulting from side impact. They are used primarily in the form of door reinforcements. Depending on the stability of the basic construction, they should have a high stiffness transverse to the direction of travel.
In side impact beams of known configuration the high stiffness is, in general, achieved by employing tubes of high-strength material. A tubular door impact beam is, for example, known from German patent documents DE 41 33 144 A1 or DE 43 04 079 A1.
In addition to side impact beams comprised of tubes, there are also impact beams which are comprised of profiled sections made of sheet metal (European patent EP 0 662 053 C1). They are mostly manufactured of conventional drawn sheet metal and have in cross-section a hat-shaped or double hat-shaped configuration. The hat-shaped profiled sections have the advantage that they are comprised of only a single part and are usually of a lighter construction in comparison to tube configurations. However, they have the disadvantage of being open at one side which causes the bending resistance to suffer. Therefore, there have been attempts to close such profiled sections. The advantages of a pipe are then transferred onto such hat-shaped profiled sections. It is known in this context to close the profiled section over its entire length or only partially across a certain area. However, this again results in increased manufacturing expenditure and increased weight.
It is an object of the present invention to produce a side impact beam with high bending resistance in a more economical way.
In accordance with the present invention, this is achieved in that the profiled section is reinforced by at least one tension element connecting the legs.
The gist of the invention is thus the measure of reinforcing the hat-shaped profile section, which is open at one side, by at least one tension element connecting the legs. Advantageously, the tension element penetrates the legs; however, this is not a requirement.
This measure substitutes the partial closing of the profiled section which has been used in the past. The invention provides a side impact beam which, with regard to manufacturing technology, is advantageous and provides a sufficiently high bending resistance. Depending on the type of vehicle and the required bending resistance, the number of tension elements can be varied accordingly. A change of the basic component geometry is not required. The minimal weight increase resulting from the presence of the tension elements is not detrimental. In comparison to closed profiled sections, the side impact beam according to the invention is expected to provide cost advantages.
An advantageous development of the basic inventive principal suggests that the at least one tension element is arranged in the central longitudinal area of the profiled sections. This can provide an approximately linear drop of the section modulus from the center toward the lateral fastening locations. Accordingly, when a central loading of a side impact beam occurs, a substantially identical bending stress along its entire length will result.
Even when principally different configurations of the tension element are conceivable, in practice it is favorable to embody the tension element either as a rod or a cable.
Such rod-shaped or cable-shaped tension elements are guided through holes produced during the manufacture of the side impact beam, are then tensioned, and secured. Expediently, the holes are produced in the sheet metal blank before its shaping. Especially advantageous with regard to practical use is a positive-locking securing of the tension elements similar to a catch or snap connection. This can be realized, for example, in that the side impact beam or its legs are manufactured with tension and the tension elements are then introduced into correspondingly designed securing openings where they are secured automatically after tension release and spring-back of the legs.
When using a cable as a tension element, it can be advantageously arranged in an S-shaped configuration by guiding it through several holes in the profiled section.
In profiled sections comprised of several hat-shaped cross-sectional portions, which are connected to one another to form a monolithic profiled part via their facing flanges, respectively, the tension element preferably penetrates both cross-sectional portions. This realizes a side impact beam which is optimized with regard to its purpose and which, while maintaining the otherwise employed dimensions of an open profiled section, has a greatly increased bending resistance.